The continuous growth of the global Internet requires that its overall architecture evolve to accommodate the new technologies that support the growing numbers of users, applications, appliances, and services. The current internet protocol (IP) address space is unable to satisfy the potential huge increase in the number of users or the geographical needs of the Internet expansion, let alone the requirements of emerging applications such as Internet-enabled wireless digital assistants, home and industrial appliances, Internet-connected transportations, integrated telephony services, and distributed computing or gaming.
The lifetime of IPv4 has been extended using techniques such as address reuse with network address translation (NAT) and temporary-use allocations. While providing some relief, these techniques present applications such as peer-to-peer communication with severe constraints. More importantly, they are becoming insufficient in addressing even the basic needs for some service providers such as multiple systems operators (MSOs).
In multiple cases, the number of managed devices, coupled with operational efficiency losses and business partner needs, already exceed the reusable address space available in IP version 4 (IPv4). Always-on environments such as residential Internet through cable modem, digital subscriber line (DSL), or Ethernet-to-the-home (ETTH), require long lasting assignments which limit the effectiveness of pooling and other temporary allocation techniques. The direct peer interaction applications, coupled with the ready-to-use capability required by consumer Internet appliances, preclude NAT techniques.
Each of these evolutions in the demand for and use of Internet services further increases the overall address requirements on the global Internet. IPv6 has the address resources to answer the increasing demand and provide a global address to all devices that require it. In RFC 3513, IP Version 6 (IPv6) Addressing Architecture In IPv6, the number of network address bits increases from 32 bits (in IPv4) to 128 bits, which provides plenty of globally unique IP addresses for the foreseeable future. The availability of global addresses can also lead to a more transparent and homogeneous Internet.
Along with these opportunities come challenges as well. The introduction of IPv6 is an intrusive endeavor. The current accounting and management systems do not directly support the new protocol and new service needs. Additionally, the network infrastructure does not adequately handle the requirements of running the IPv4 and IPv6 protocols simultaneously. For example, services such as VoIP have been very successful for cable providers and it is important that their performance and operation is not affected by the coexistence of the two versions of IP. A stable migration path to ensure the successful introduction of this extensible feature rich protocol is paramount.